1. Field of the Invention
This invention relates to dry shavers and more particularly to dry shavers having a shearing foil clamped to a holder adapted to move the shearing foil between different wrap angles.
2. Description of the Prior Art
A dry shaver with a working combination of movable cutter and a shearing foil clamped in a curved fashion to longitudinally extending side walls of a holder detachably mounted on a shaver housing is disclosed in U.S. Pat. No. 3,440,724.
To be able to remove the prior art shearing foil holder from the cutter, the shearing foil could not undercut or be wrapped anywhere beneath the cutter, as the cutter would otherwise interfere with the removal of the shearing foil holder. The admissible wrap angle of the shearing foil can for this reason not be greater than 180.degree.. In practice, a wrap angle of about 120.degree. is chosen so that during removal, the shearing foil is at once free from the cutter and is not damaged by the latter.
This relatively small wrap angle has the drawback that the active cutting area of the dry shaver is comparatively small. This results in a lower cutting efficiency. The prior art shearing foil holder dimensions are relatively large close to the housing of the dry shaver to provide clearance so that the holder can be immediately set free from the cutter when removed from the housing, whereby the dry shaver must be considerably thicker than the diameter of the cutter. Thus it has a clumsy shape which is not only unattractive looking, but also disadvantageously affects its handling properties.
Older dry shavers are known in which the shearing foil, without additional reinforcement or a removable holder, is simply clamped over the cutter (German Pat. No. 802,052). With these designs greater wrap angles can be used, as the shearing foil is not lifted off but is wound off the cutter. Aside from other basic defects of such designs, it has also proven disadvantageous that the shearing foil, which because of its small thickness of 0.05 mm approximately is very delicate is frequently damaged by too tight clamping on the cutter or by other improper handling. Aside from that, the removal and reclamping of the shearing foil required considerable effort and skill, so that the work necessary to clean the dry shaver was often considered a nuisance.
Another known alternative of achieving a large wrap angle involves shaping the shearing foil as a tube or tube section which is longitudinally slid over a cylindrical cutter. In practice, these designs have also not prevailed because the highly vulnerable shearing foil can be damaged during the slide-on process by the edges of the individual cutting blades of the cutter. This applies especially to the front edge of the shearing foil which lies unprotected during the slide-on process.
An object of the present invention is to develop a dry shaver of the type mentioned at the outset in which on the one hand the shearing foil may undercut the cutter and be wrapped around at an angle of more than 180.degree., while on the other hand it is still possible to remove the shearing foil, without the danger of damage, quickly and simply from the cutter to expose the latter for inspection and cleaning. This task is solved by the invention in that at least one of the side walls is designed so that it can at least partially be swung out around a pivot axis running longitudinally to the blade head.
With the invention, this solution is possible both with dry shavers having a cutter moving back and forth, as well as with dry shavers of other designs having a cutter-foil system, e.g., a dry shaver with a cutter roller rotating around a horizontal axis or a cutter arrangement moving pendulum-like. An advantage of the present invention applies to dry shavers in which the shearing foil undercuts the cutter or is wrapped around it at more than 180.degree., since the shearing foil can easily and quickly be removed and reattached to the cutter without the danger of damage. Since removal and reattachment of the shearing foil is usually carried out after every use of the dry shaver to clean the cutter with a brush, the handling of the dry shaver is greatly facilitated by this simplification and improvement.
A further advantage is that the shearing foil holder in its operating position can be narrower than the diameter of the cutter. This causes the shaver body to be slimmer than the customary dry shavers. An additional advantage of the invention must be pointed out, namely that the shearing foil holder with the shearing foil can be cleaned better than a traditional shearing foil holder.
It is not absolutely necessary to construct the side walls of the shearing foil holder in such a fashion that they can be swung out completely. It is sufficient if the respective side wall can be swung out partially, namely always in accordance with the measurements of the shearing foil, with that portion of the side wall which carries the holding means for the shearing foil.
An advantageous embodiment of the invention includes a side wall that can be locked in an operating position by means of a catch device, in which the shearing foil is wrapped around the blade head in a large wrap angle. This form of construction is especially expeditious from the structural viewpoint and particularly simple in handling. Compared with the traditional dry shavers with shearing head frame or foil holder, only one additional work step is required to remove or reattach the shearing foil holder with the shearing foil, namely the swinging-out or swingin-in of the one side wall or at least one part of it.
An especially large wrap angle of the shearing foil can be achieved if another advantageous construction of the invention is followed, namely the shearing foil holder is formed by two holder parts which can be rotated in pincer-fashion around a common axis.
Additional advantages of the invention will be apparent from the following description of two of the many construction possibilities of the invention.